[userbinator]

The target catastrophic failure rate there is 1 in a billion hours, which doesn't seem all that high to me... there are over 100000 flights a day[1], and the average length of one is well over an hour, so in one day all the aircraft in the world have accumulated a total of over 2.4 million hours in operation. If each flight was only an hour long, that's 417 days to 1 billion total hours, and if the failure rate really was 1 in a billion we'd expect to see one of these happen at almost yearly rates.

The actual failure rate of software to this standard seems to be at least two orders of magnitude higher.

[1] http://www.garfors.com/2014/06/100000-flights-day.html

[peeters]

Where is the "actual failure rate" number coming from?

[branchan]

How does 100k flights a day equal 2.4 millions hours of operation if each flight was on average 1 hour?

[grkvlt]

Yeah, confused. If we assume a two hour average flight, we get 365 * 2 * 100K = 73M hours/year so one failure per 1G hours is one failure in 1000 / 73 = ~14 years.